The present invention generally relates to orthopedic medicine, and more particularly to systems and methods for spinal fixation.
Spinal plate systems are commonly used to fix adjacent vertebrae when treating spinal fractures or disorders, and for fusion of vertebrae.
In some instances it is desirable to create compression between adjacent vertebrae, to enhance the bone to graft apposition and provide for better fusion. Compression may be difficult to create and to maintain. If a bone screw feature is used to create the compression, backout of the bone screw can be a common problem, as the screw may work its way backwards out of the bone. Backout prevention features have been designed which are complicated mechanisms with multiple parts. It would be desirable to have a compression screw retention feature which is a monolithic part of the bone plate.
Another important aspect of bone plating systems is the orientation of the fixation members which fix the spinal plate to the vertebrae. Fixation members should pass through hard cortical bone to firmly fix the plate to the vertebrae. Additionally, the fixation members must avoid nervous and vascular structures enclosed by and adjacent to the vertebrae. Each fixation member may require a separate orientation which must be permanently fixable. Therefore, it is desirable to provide a system to individually guide the fixation members and lock their orientations relative to the vertebrae.
The shape and curvature of a spinal plate is significant feature of its design. A plate with a straight or flat bone apposition surface may be difficult to fix to the vertebral surface, as gaps may be present between the surface of the vertebral bodies and the plate. There is need for a plate which is not only curved to match the lordotic curve of the spine, but also has a bone apposition side shaped to conform to the surfaces of the vertebrae.